Identification of SNPs associated with fatty acid contents in mutant soybean lines by a genome-wide association study.

Background: Vegetable oils are primarily composed of unsaturated fatty acids. Soybean [Glycine max (L.) Merr.] oil, accounting for 28% of the global production of vegetable oil, contains mainly two saturated fatty acids (palmitic acid and stearic acid) and three unsaturated fatty acids (oleic acid, linoleic acid, and linolenic acid) in seeds.

Objective: The five fatty acids determine soybean oil quality. We aimed to identify genetic relationship between genomics and fatty acid contents in soybean mutant pool.

Methods: This study used a mutant diversity pool (MDP) comprising 192 soybean lines. A genome-wide association study (GWAS) was conducted with the diverse fatty acid contents in MDP and 17,631 filtered SNPs from genotyping-by-sequencing (GBS).

Results: The GWAS revealed nine significant SNPs within intragenic regions that were associated with fatty acid composition. These SNPs corresponded to six genes (Glyma.03g042500, Glyma.07g069200, Glyma.13g150200, Glyma.14g223100, Glyma.15g084700, and Glyma.15g274000), of which three (Glyma.03g042500, Glyma.13g150200, and Glyma.15g274000) were predicted to be candidate genes influencing oleic acid, linoleic acid, and linolenic acid contents. Analyses of SNP allelic effects revealed the largest and smallest significant differences in fatty acid contents were 5.53% (linolenic acid) and 0.4% (stearic acid), respectively.

Conclusion: The present study detected significant phenotypic variations and genetic associations underlying the fatty acid composition of soybean seeds in MDP lines. The mutant seeds differed from the original cultivars in terms of fatty acids composition, with the allelic effects of significant SNPs influencing the fatty acid content in seeds. These findings may be useful for enhancing breeding strategies to optimize soybean oil quality for various uses.